Self-cleaning filter assembly

ABSTRACT

A fluid filter assembly having a body with a chamber for receiving a filter element supported by the body. At least one cleaning device is positioned adjacent the inlet side of the filter element. The cleaning device includes a hollow duct for collecting dislodged particulate matter, an adjustable scraper or brush and a deflector substantially equal in length to the scraper or brush. Nozzles may be provided for directing pressurized cleaning fluid toward the cleaning device.

This application is a continuation of U.S. patent application Ser. No.08/136,953 filed Oct. 13, 1993, now U.S. Pat. No. 5,443,726.

BACKGROUND OF THE INVENTION

1. Field of The Invention

This invention relates to improvements in self-cleaning filters. Moreparticularly, this invention relates to filters for fluid media carryingfibrous or other forms of debris which tend to clog the filters.

2. Description of the Prior Art

Strainers and filters are employed to separate solids from fluids.Generally speaking, strainers are used to separate solids with anaverage width of 1/2 inch to 75 microns. Filters are used to separatesolids with an average width less than 75 microns. In the case ofstrainers, the solids are collected on a screening media or strainerelement and thereafter, the solids are removed from the screening mediaby backwashing. During backwashing, fluid is caused to flow in a reversedirection through the screening media and is collected by a backwash armto clean the screen, as described, for example, in U.S. Pat. Nos.4,818,402 and 5,152,891, which are hereby incorporated by reference. Asused herein, the term "backwash arm" refers to a suction chamber orcollection duct.

Filters typically collect solids in a disposable bag filter element orare provided with brushing or blow down systems to remove the collectedsolids. A shortcoming of bag filters is that they are expensive. In manycases the collected solids, such as hydrocarbon materials, must beplaced in special containers and sent to landfills. Further, the brushand blow down type systems are inefficient and periodically require handcleaning of the filter element resulting in expensive downtime and laborcosts.

Accordingly, it is an object of this invention to provide a filter thatis less expensive and more efficient to operate than the prior artfilters.

SUMMARY OF THE INVENTION

Briefly, according to this invention, there is provided a filterassembly comprising a body defining a chamber for receiving acylindrical filter element. The space outside the filter elementcomprises an inlet cavity. The filter element is positioned within thechamber and attaches to the body. The cylindrical filter element has anexternal inlet side and an internal outlet side. Fluid being filteredpasses through the inlet side and then through the outlet side of thefilter element. According to this invention, at least one device forcleaning the inlet side of the filter element is provided within theinlet cavity of the chamber. The device for cleaning includes a hollowduct for collecting particulate matter dislodged from the inlet side ofthe filter element. The duct is positioned with an inlet slot openingadjacent to the inlet side of the filter element. The duct and thefilter element are mounted to be movable relative to each other. Anadjustable scraper attaches to the duct and slidably contacts the inletside of the filter element. The scraper is substantially equal in lengthto the slot opening in the duct. A fluid deflector attaches to the duct.The deflector is substantially equal in length to the scraper. Thedeflector is positioned forwardly of the scraper as the filter elementrotates toward the duct. The slot opening is positioned between thedeflector and the scraper. The deflector has a leading edge positionedin close proximity to the inlet side of the filter element. A cleaningchamber is defined by the scraper, the deflector and the duct. Thecleaning chamber is in communication with the inlet surface of thefilter element whereby during a backwash mode, the duct and the filterelement move relative to each other and fluid is directed into thecleaning chamber and then into the duct.

According to a preferred embodiment, a second cleaning device isprovided which is similar to the first cleaning device, and includes asecond duct having a second slot, a second adjustable scraper and asecond deflector. The first slot is spaced approximately 180° from thesecond slot and the first slot can be positioned adjacent a firstvertical section of the filter element and the second slot is positionedadjacent a second vertical section of the filter element. The firstsection of the filter element is positioned above the second section ofthe filter element.

According to a preferred embodiment, nozzle devices are provided fordirecting pressurized cleaning fluid at a pressure greater than thefluid pressure of the fluid being filtered through the filter elementagainst the inlet side of the element for dislodging particulate matterfrom the inlet side of the filter element adjacent the deflector.

Preferably, the deflector has a forwardly extending edge adjacent theinlet side of the filter element which constricts the flow into thecleaning chamber so that the velocity of the fluid increases as itenters the chamber to better sweep loosened debris from the inlet sideof the filter.

Preferably, the scraper has a trapezoidal cross section with an edgedefined by the corner of the trapezoidal cross section being in contactwith the inlet side of the filter. The scraper may be made of apolymeric material, such as TEFLON® or DELRIN®, or a soft metal such asbrass. The scraper must be softer than the filter element normallycomprised of a stainless steel wedge wire so that the filter element isnot worn away. A scraper shoe may be provided to receive the scraper.The shoe attaches to the duct. A device is provided for adjusting theposition of the scraper edge to abut the inlet side of the filterelement. The adjusting device may include a threaded adjustment memberthat contacts with the scraper and the scraper shoe.

In another preferred embodiment, a brush having a plurality of bristlescan replace the above-identified scraper.

A motor is provided mounted to the body so that when the motor isactivated, relative rotation of the filter element and the cleaningdevice takes place.

This invention also relates to a method for modifying a filter having abody, a filter element, a hollow duct for collecting dislodgedparticulate matter and an adjustable scraper by arranging nozzlesadjacent to the inlet side of the filter element where the nozzlesdirect pressurized cleaning fluid maintained at a pressure greater thanthe fluid pressure of the fluid being filtered flowing through thefilter element against the inlet side of the filter element fordislodging particulate matter from the inlet side of the filter elementand connecting a source of pressurized cleaning fluid to the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a filter, partially in section, illustratingthe present invention;

FIG. 2 is top view, partially in section, of a portion of the filtershown in FIG. 1;

FIG. 3 is a side view, partially in section, of a subassembly of thefilter shown in FIG. 1;

FIG. 4 is a top view of the subassembly shown in FIG. 3;

FIG. 5 is a side view, partially in section, of a sealing and bearingarrangement for the filter shown in FIG. 1;

FIG. 6 is a side view of a second embodiment of a self-cleaning filter,partially in section, made in accordance with the present invention;

FIG. 7 is a top view, partially in section, of a lower portion of thefilter shown in FIG. 6;

FIG. 8 is a side view, partially in section, of a subassembly of thefilter shown in FIG. 5;

FIG. 9 is a top view of the subassembly shown in FIG. 8;

FIG. 10 is a top view, partially in section, of an upper portion of thefilter shown in FIG. 6;

FIG. 11 is a side view of a spray nozzle arrangement made in accordancewith the present invention;

FIG. 12 is a front view of the spray nozzle arrangement shown in FIG.11;

FIG. 13 is a top view of the spray nozzle arrangement shown in FIGS. 11and 12;

FIG. 14 is a section taken along lines XIV--XIV in FIG. 11;

FIG. 15 is a top view, partially in section, of another embodiment of aself-cleaning strainer similar to that shown in FIG. 2;

FIG. 16 is a side view, partially in section, of a subassembly of thefilter shown in FIG. 15; and

FIG. 17 is a side view, partially in section, of another embodiment of aself-cleaning strainer, similar to that shown in FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 5 illustrate a first embodiment according to this inventionof a filter assembly 10 having a cylindrical body 12 with asubstantially closed top 14 and a substantially closed bottom 16. Thebottom 16 includes a drain port 17. A support plate 18 is positionedabove the bottom 16 and includes a recess for receiving a filterelement. An annular shaped wear ring 19 is positioned at a base of therecess. The filter assembly 10 also includes a cylindrically shapedfilter element 20 having an external inlet side 22 and an internaloutlet side 24. A blind disc 25, which is circular, is welded to abottom end of the filter element 20, thus forming a closed bottom opentopped cylindrical structure. Preferably, the filter element 20 is ahollow cylinder made of stainless steel wedge wire defining a pluralityof slots each having a slot width of about 25 to 50 microns. Filterelements of this type are manufactured by Johnson Corporation and LeemFiltration, Inc., for example.

The body 12 includes an inlet port 26a and an outlet port 26b. An inlettube 28a is in fluid communication with the inlet port 26a and is weldedto the body 12. Likewise, an outlet tube 28b is in fluid communicationwith the outlet port 26b and is welded to the body 12. An annularalignment plate 29 is welded to a lower end of the body 12. An innersurface of the alignment plate 29 slidably receives an outer surface ofthe support plate 18. Bolts 30 attach the alignment plate 29 to thebottom 16.

Filter element 20 is concentrically disposed inside the body 12 whereinthe disc 25 is journaled in the recess of the support plate 18 and restson wear ring 19 (see FIG. 3). The filter element 20 is journaled at theupper end thereof by a locking arrangement 40 comprising an annularupper support plate 42 which is attached to a mounting plate 44 throughpins 46 and 48. Support plate 42 rests on annular mounting plate 44secured to the inside of the cylindrical body 12. Pins 46 and 48 arereceived by both plates 42 and 44. Two threaded holes spaced apart byapproximately 180° pass through plate 42. Threaded plugs 47a and 47b(see FIG. 4) are received by the holes in support plate 42. The annularmounting plate 44 attaches to the cylindrical body 12 through weldingand is positioned below the outlet tube 28b. An O-ring 50 is received byan O-ring slot 52 defined on the support plate 42. The O-ring iscaptured between the support plate 42 and the mounting plate 44 therebyforming a fluid tight seal.

An annular shaped cap 54 (see FIG. 5) is attached to and supports theupper end of the filter element 20. The cap 54 includes an O-ring slotthat receives an O-ring or sealing member 55 which is captured betweenthe cap 54 and an inner surface of the support plate 42 in which it isjournaled. A retainer ring 56 is positioned above cap 54. Ring 56 alsoincludes four integral tabs 58. The tabs 58 are spaced 90° apart. Afastener 60, such as a bolt, passes through each tab 58 and intothreaded holes provided in the support plate 42 thereby holding the cap54, through ring 56, in place. As is evident, ring 56 is secured tosupport plate 42. A V-shaped annular space 61 is defined by outer edges62 and 63 of the plate 42 and cap 54. A V-shaped cross section annularbearing 64 is received in annular space 61. Preferably, the bearing 64is made of plastic or brass. The bearing 64 is held in place by a bottomsurface of an annular retaining lip 65 that is integral to and dependsfrom ring 56. The force applied by the ring 56 via the fasteners 60causes bearing 64 to be wedged between cap 54 and plate 42 and acts as abearing surface for cap 54 and as a fluid seal between outer edges 62and 63 should the O-ring 55 fail.

The upper chamber 66 is defined above filter element 20 and filterelement 20 is contained within the lower chamber 68. Accordingly, thefilter element 20 is fixed along the cylindrical axis thereof but canrotate about the axis. Furthermore, this arrangement results in a fluidtight seal between an upper chamber 66 and lower chamber 68 of thefilter assembly except for the liquid which passes through filterelement 20.

A substantially rectangular shaped drive bar 80 (see FIG. 4) is attachedto the cap 54 at the upper surface of the filter element 20. Bar 80 ispositioned transverse to the cylindrical axis of the filter element axisand bar 80 is adapted to be turned about the cylindrical axis.

A cylindrical drive shaft 84 having a rectangular shaped drive slot 85at a lower end thereof passes through the upper chamber 66. The slot 85receives the drive bar 80 as shown in FIG. 1. The drive shaft 84 passesthrough a centrally positioned hole located in the top 14. Packingmaterial lines the hole and is captured between the top 14 and the shaft84. The shaft 84 passes through a gear reducer mount 86 and is receivedby a gear reducer 88. The gear reducer is mechanically coupled to adriving motor 90.

The filter assembly 10 further includes a first cleaning assembly 100that includes an elongated hollow square cross-sectionally shapedbackwash arm 102 extending in the longitudinal direction defined bysidewalls (see FIG. 2). A longitudinally extending slot or passageway104 passes through an upper portion of a sidewall of the arm 102 facingthe filter element in an upper section 105 (see FIG. 3) of the backwasharm 102. The backwash arm 102 also includes a closed upper end 106. Alongitudinally extending scraper 108 is attached to a wall of arm 102 ata rearward portion of the backwash arm 102 adjacent to and approximatelyequal in length to slot 104. Preferably, the scraper 108 has atrapezoidal cross section with a tip 112 contacting the filter elementinlet side 22. The scraper 108 is slidably received by a longitudinallyextending shoe 114. The shoe 114 has a flange and a substantiallyL-shaped section secured thereto. The flange attaches to the backwasharm 102, whereby a scraper receiving recess is defined by the shoe 114and a wall of the arm 102. Holes are provided in the shoe 114 for bolts115 (of which only one is shown). Two locking nuts 117 and 118 arethreadably received by each bolt. Locking nut 117 is welded to the shoeadjacent the hole. A longitudinally extending scraper plate 119 iscaptured between scraper 108 and shoe 114. Forward ends of the bolts 115abut and push the scraper back plate 119 against a rear face of thescraper 108. Accordingly, the position of the scraper tip 112 can beadjusted to abut filter element inlet side 22 by rotating the bolt 115in a clockwise direction until tip 112 contacts side 22 and thentightening nuts 118 so that nuts 118 abut nuts 117 locking the scraper108 in place. The scraper 108 can be readjusted by loosening the nuts118 and repeating the above procedure. The length of the upper section105 of the backwash arm 102 is about half the total length of the filterelement 20. Preferably, the scraper 108 is made of a polymeric materialsuch as TEFLON® and DELRIN® or a soft metal such as brass.Alternatively, springs can be provided between scraper back plate 119and the second shoe section so as to continually urge tip 112 againstthe filter element 20. This would eliminate the need for adjusting thescraper 108 due to wear.

A deflector 120 is positioned on a forwardly portion of the backwash arm102 (see FIG. 2). The deflector 120 is substantially L-shaped andincludes a first section 122 positioned forwardly of the backwash arm asthe filter element rotates toward the arm and a second section 124 whichis attached to the backwash arm 102. Preferably, a 0.5 inch or less gap130 is provided between a forwardly extending edge 132 of the firstsection 122 of the deflector arm 120 and the filter element 20. Thisdeflector arm 120 is adapted to direct cleaning fluid in a tangentialdirection to the filter element 20 and then into the slot 104 as will bediscussed below.

An upper plate 134 (see FIG. 4) is attached to arm 102 adjacent theupper end of the scraper assembly 108 and the deflector 120. A lowerplate 136 is attached to arm 102 adjacent the lower end of the scraperassembly 108 and the deflector 120. A lower end of scraper 108 rests onplate 136. A cleaning chamber 137 (see FIG. 2) is defined by the upperplate 134, lower plate 136, a wall of the arm 102, scraper 108 anddeflector 120.

A hollow lower section 138 (see FIG. 1) of the backwash arm 102 extendsbelow slot 104 and includes a flanged lower end 140, which rests on thesupport plate 18 and above a hole 150 that passes through the supportplate 18. The flanged lower end 140 and closed upper end are bolted toplates 18 and 42, respectively. The hole 150 leads into a cavity 160defined between the support plate 18 and the closed bottom 16. Hence,the chamber 138 of backwash arm 102 fluidly communicates with the cavity160 through the hole 150.

A second cleaning assembly 200 is spaced apart approximately 180° fromthe cleaning assembly 100. The second cleaning assembly 200 is similarto the first cleaning assembly and includes an elongated hollow squarecross-sectionally shaped backwash armor duct 202 extending in thelongitudinal direction defined by sidewalls and a longitudinallyextending slot or passageway 204 passes through a sidewall of the arm202 in a lower section 205 of the backwash arm 202. The backwash arm 202has a closed upper end 206. A longitudinally extending scraper 208 isattached to a wall at a rearward portion of the backwash arm 202adjacent to and approximately equal in length to slot 204. Preferably,the scraper 208 has a trapezoidal cross section with an edge 212contacting the filter element inlet side 22. The scraper 208 is slidablyreceived by a longitudinally extending shoe 214.

The means for securing and adjusting the scraper 208 and shoe 214 areidentical to those for securing scraper 108 in shoe 114. Elements 202 to218 correspond to elements 102 to 118, respectively.

The means for directing cleaning fluid on filter element 20 comprisedeflector 220 and other elements. Elements 220 to 240 of arm 202correspond to elements 120 to 140, respectively, of arm 102.

As can be seen from FIGS. 1 to 4, the slots 104 and 204 and scrapers 108and 208 are spaced 180° apart. Furthermore, slot 104 and scraper 108 arepositioned adjacent an upper portion 260 of the filter element 20 andthe slot 204 and scraper 208 are positioned adjacent a lower portion 270of the filter element 20, wherein the upper portion 260 and the lowerportion 270 are equal in length to approximately one-half the length ofthe filter element so along the cylindrical axis thereof.

An effluent cavity 300, as shown in FIG. 1, is defined in the upperchamber 66. The outlet tube 28b is in fluid communication with cavity300. A high pressure fluid cleaning plate 302 attaches to an outersurface of the body 12 adjacent to the fluid cavity 300. Plate 302includes a threaded hole 304 that threadably receives a plug 305. A hoseconnecting plate 306 having threaded holes 308 and 312 is welded to aninside surface 314 of body 12 that defines a filter chamber 302. Apassage 316 is provided in surface 314 so that hole 304 is in fluidcommunication with holes 308 and 312.

In filter mode operation, a supply of unfiltered fluid passes to inletport 26a. The drain port iS connected to a valve, which exits toatmospheric pressure, and a tank (not shown). As shown in FIG. 1, theunfiltered fluid passes through the inlet tube 28a, through the filterelement 20, thereby becoming filtered fluid. The filtered fluid thenflows upwardly into cavity 300 through an opening 340 defined by innersurface of support plate 42, cap 54 and retaining ring 56, and thendischarges through outlet 28b as shown by the arrows in FIG. 1.Particulate matter (filtrate) is separated from the unfiltered fluid andlodged on the inlet side 22 of the filter element 20 as the filteredfluid passes through the filter element 20.

At spaced time intervals during backwash mode operation, the motor 90and the gear reducer 88 are activated thereby causing the shaft 84 torotate in a clockwise direction, which in turn rotates the filterelement 20 through drive bar 80 in a clockwise direction ω about thecylindrical axis of the filter element axis. This in turn causes thescraper edges 112, 212 to scrape debris or particulate matter contactingthe inlet side of the filter element 20. Simultaneously, a valve (notshown) in communication with the exit port 17 is opened resulting inpressurized fluid flowing from both the inlet side 22 and outlet side 24of the filter element 20 into the backwash arms 102, 202. The fluidpositioned adjacent to the deflector arms 120 and 220 is directed toslots 104 and 204, respectively, as indicated by the arrows in FIG. 2.Unfiltered fluid guided by the deflector arms 120 and 220 tangentiallyflows against the filter element 20 which further causes additionalparticulate debris to be removed from the filter element, as shown inFIG. 2. The velocity of the tangentially flowing fluid is a function ofthe rotational speed of the filter element and the pressure of the fluidcontained within the lower chamber 68.

Generally speaking, the higher the operating pressure the higher thetangential velocity, which in turn has a greater effect on removingdebris and particulate matter. Accordingly, debris and particulatematter removed by the scrapers 108 and 208, the tangentially flowingfluid and filtered fluid flowing passing back through the filter element20 adjacent chambers 137 and 237, passes through chambers 137 and 237,slots 104 and 204, down the respective backwash arms or ducts intocavity 160 and outlet port 17 to the tank for subsequent removal.

After a period of time, the motor 90 is deactivated stopping therotation of the filter element 20 and the valve controlling exit port 17is closed preventing the flow of fluid through the backwash arms intothe tank.

Activation of the backwash mode can be done manually or automatically.Further, the motor can be activated as a function of a specific timeinterval, say 2 hours, or as a function of the fluid pressure dropacross the filter element 20 which is indicative of the amount of debrisor particulate matter lodged on the filter element 20.

Spacing the two backwash arms 102, 202, 180° apart and having backwasharm 102 positioned adjacent the upper portion 260 of the filter element20 and the backwash arm 202 positioned adjacent the lower portion 270 ofthe filter element 20 results in superior cleaning. It has been foundthat in cases where only one backwash arm is used over the entire lengthof the filter element, only a portion of the filter element is cleaned.Further, superior performance is obtained by having scraper 108 contactthe filter element 20 as opposed to the teachings of U.S. Pats. Nos.4,818,402 and 5,152,891, which teach spacing the scraper elements fromthe strainer element. It is important to note that alternatively thecleaning assemblies 100, 200 could rotate and the filter backwashelement remain stationary. In that case, the cleaning assemblies 100,200 rotate counterclockwise so that effective cleaning could occur.Also, both the filter element 20 and cleaning assemblies 100, 200 couldrotate.

In some instances, though, especially when the filter assembly 10 isutilized in low operating pressure applications, it is preferable toutilize a nozzle arrangement discharging high pressure cleaning fluidagainst the filter element 20 in combination with backwash armspreviously discussed. Accordingly, FIGS. 6 to 14 illustrate a secondembodiment of the invention. The filter assembly 10 of the secondembodiment utilizes many of the same elements as the previouslydescribed for the first embodiment and, accordingly, like referencenumerals will be used for like parts.

Filter assembly 10 further includes a nozzle assembly 400 that includesa hollow shaft 402 having an open upper end 404 and a closed lower end406. A plurality of holes 408 are positioned in an upper portion of thehollow shaft 402. A plurality of nozzles 410 direct high velocitycleaning fluid toward a forward portion of the first section 122 of thedeflector 120 so that the high velocity cleaning fluid passes throughgap 130 approximately tangent to the adjacent filter element 20. Thenozzles are positioned forwardly of the gap 130.

As shown in FIGS. 13 and 14, each of the nozzles 410 includes a head 412and a threaded body 414. A deflector tip 416 is provided on the head 412of the nozzles 410. Stabilizing plates 418 are provided on the upper andlower surfaces of the shaft 402. Stabilizing plates 418 are attached toplates 18 and 42 by welding, or threaded fasteners 419 or any other typeof fastener.

A hose 420 (see FIG. 10) is provided having threaded ends 422 and 424.Hose 420 is in communication with the hollow interior of shaft 402.Specifically, end 424 is threadably received by hole 308 of plate 306.

A second nozzle assembly 500 is similar to that of nozzle assembly 400.Elements 500 to 525 correspond to elements 400 to 425, respectively.

A source of high pressure cleaning fluid is connected through a valve tothe hole 304 of plate 302 thereby passing high pressure cleaning fluidto the nozzles 510 and 410 via the hoses 520 and 420.

Preferably, the nozzle tips 416, 516 are positioned adjacent to, inclose proximity to, and forwardly of the inlet side of the deflectoredges 132, 232, respectively, so that during the backwash more highvelocity cleaning fluid exiting the nozzles 410, 510 contact the inletside 22 of the filter element 20 dislodging particulate matter whichenters the inlet end of the backwash arm. Preferably, the nozzlesdischarge cleaning fluid at an acute angle, such as 45° with respect tothe tangent of the inlet side of the filter element at the point ofcontact of the directed cleaning fluid. One supplier of nozzles 410, 510is Spraying Systems Co.

The operation of the second embodiment is substantially identical to theoperation of the first embodiment. In the backwash mode of the secondembodiment, nozzle assemblies 400 and 500 may be activated. However, itmay not be necessary to activate the nozzles for every backwash mode.

In some instances, the purchaser of a filter assembly according to thefirst embodiment may desire to upgrade the filter assembly to includenozzle assemblies 400, 500. In that case, the nozzle assemblies may beinstalled by removing plugs 47a, 47b and 305 and attaching the nozzleassemblies 400 and 500 to the plates 18 and 42 the attaching the hoses420 and 520 to plate 306 as previously explained.

FIGS. 15 and 16 show another embodiment of the present invention. Thisembodiment has all of the same elements as the filter assembly 10 shownin FIGS. 1-5 with the exception of elongated scrapers 108 and 208 havebeen replaced by elongated brushes 108' and 208' made up of a pluralityof bristles 112' and 212'. The bristles can be made of a polymermaterial, such as nylon, or a soft metal. Tips of bristles 112' and 212'slideably contact the filter inlet side 22. Bristles 112' and 212' aresecured to respective back plates 119 and 219. Brushes 108' and 208' aresecured to shoes 114 and 214 respectively by screws (not shown). Bolts115, 215 and bolts 117, 217 and 119, 219 are not necessary in thisembodiment. The brushes 108' and 208' function in the same manner asscrapers 108 and 208, that is, to remove particulate matter from thefilter.

Each brush 108' and 208' is attached to the respective ducts or arms102, 202 through the respective shoes 114 and 214, so that the bristlesslideably contact the inlet side 22 of the filter element 20. Each brush108' and 208' is substantially equal in length to the respective slotopenings 104, 204. The deflectors 120, 220, which are positionedforwardly of the brushes 108' and 208', are substantially equal inlength to the respective brushes 108', 208'. Each respective slotopening 104, 204 in the duct 102, 104 is positioned between respectivedeflectors 120, 220 and respective brushes 108', 208'. The respectivedeflector 120', 220' leading edges are positioned in close proximity tothe filter element 20. Each respective cleaning chamber 137, 237 isdefined by a respective brush 108', 208', deflector 120, 220 andcleaning duct 102, 202.

This embodiment operates in a similar manner as the filter shown inFIGS. 1-5, i.e., fluid to be filtered passes from the inlet through thefilter element and to the outlet, and the filter element moves relativeto the ducts, or vice versa, so that fluid is directed from the inletcavity into the cleaning chamber and the duct through which it can bedirected to the backwash outlet. Preferably, the brush is a sealing typebrush, adapted to prevent, as much as possible, the directed fluid fromflowing from the cleaning chamber through the brush. Sealing typebrushes are sold by Sealeze Corporation of Richmond Va. andMcMaster-Carr Supply Company of New Brunswick N.J. (Part Number74405.T81).

FIG. 17 shows another embodiment similar to the embodiment shown in FIG.8 except the scrapers 108 and 208 are replaced with brushes 108' and208' of which only brush 208' is shown. It is also our belief that thescrapers or scraping bars disclosed in U.S. Pat. Nos. 4,818,402 and5,152,891 can also be replaced by brushes similar to those disclosedherein.

Having described the presently preferred embodiments of the invention,it is to be understood that it may otherwise be embodied within thescope of the appended claims.

We claim:
 1. A fluid filter assembly comprising:a filter body defining achamber, an inlet, an outlet, and a backwash outlet; a cylindricalfilter element positioned within said chamber and supported by said bodythrough which a fluid entering the inlet must pass to exit the outlet,said filter element having an inlet side and an outlet side, said filterbody and the inlet side of said cylindrical filter element defining aninlet cavity; means for cleaning the inlet side of the filter elementcomprising: a hollow duct for collecting particulate matter dislodgedfrom said filter element, said duct supported by said body andpositioned within said inlet cavity adjacent to said inlet side of saidfilter element, said duct and said filter element being movable relativeto each other, said duct including a slot opening so that said duct isin fluid communication with said inlet cavity; an elongated adjustablescraper attached to said duct and slidably contacting the inlet side ofsaid filter element, said scraper substantially equal in length to saidslot opening; a fluid deflector attached to said duct, said deflectorsubstantially equal in length as said scraper, said deflector beingpositioned forwardly of said scraper, said slot opening in said ductbeing positioned between said deflector and said scraper, said deflectorhaving a leading edge positioned in close proximity to said filterelement; a cleaning chamber defined by said scraper, said deflector, andsaid duct, said cleaning chamber in fluid communication with said inletcavity; whereby when a fluid to be filtered passes from the inletthrough the filter element and to the outlet and said duct and saidfilter element move relative to each other, fluid is directed from saidinlet cavity into said cleaning chamber and said duct through which itcan be exhausted to said backwash outlet.
 2. A fluid filter assembly asclaimed in claim 1 further comprising:a nozzle means for directingpressurized cleaning fluid maintained at a pressure greater than thepressure of the fluid flowing through the filter element against theinlet side of the filter element for dislodging particulate matter fromsaid inlet side of the filter element, said nozzle being positionedwithin the inlet cavity and adjacent to said inlet side of the filterelement and said means for cleaning.
 3. A fluid filter assembly asclaimed in claim 1 further comprising an upper plate attached to saidduct adjacent an upper portion of said scraper and an upper portion ofsaid deflector and a lower plate attached to said duct adjacent a lowerportion of said deflector and a lower portion of said scraper.
 4. Afluid filter assembly as claimed in claim 1 further comprisingadditional means for cleaning the inlet side of the filter element asset forth in claim
 1. 5. A fluid filter assembly as claimed in claim 4wherein said cleaning means are equally spaced along the inlet side ofthe filter element.
 6. A fluid filter assembly as claimed in claim 4wherein the inlet side of said filter element has first and secondvertically spaced portions and different cleaning means are arranged toclean the surface of each spaced portion.
 7. A fluid filter assembly asclaimed in claim 5 wherein two cleaning means are spaced approximately180° apart and a first portion of the inlet side of said filter elementis positioned above a second portion.
 8. A fluid filter assembly asclaimed in claim 7 further comprising nozzle means associated with eachcleaning means for directing pressurized cleaning fluid maintained at apressure greater than the filter pressure of the fluid being filteredflowing through the filter element against the inlet side of the filterelement for dislodging particulate matter from said inlet side of thefilter element adjacent said means for cleaning, said nozzle meanspositioned within the inlet cavity and adjacent to said inlet side ofthe filter element.
 9. A fluid filter assembly as claimed in claim 1wherein said deflector has an edge positioned forwardly of said slotopening as the cleaning means and inlet side of the filter element moverelative to each other, said edge positioned in close proximity to theinlet side of said filter constricting the flow of fluid into thecleaning chamber whereby the velocity of the fluid increases as itenters the cleaning chamber.
 10. A fluid filter assembly as claimed inclaim 9 wherein said deflector includes a first section attached to asecond section, said first section includes said first end and dependsfrom said second section, said second section is attached to said duct.11. A fluid filter assembly as claimed in claim 10 wherein saiddeflector is L-shaped.
 12. A fluid filter assembly as claimed in claim 1wherein said scraper has a trapezoidal cross section and an edge of saidscraper contacts the inlet side of said filter.
 13. A fluid filter asclaimed in claim 12 wherein said scraper is made of a polymericmaterial.
 14. A fluid filter assembly as claimed in claim 1 furthercomprising a scraper arm shoe adapted to receive said scraper, said shoeattached to said duct, said scraper having an edge biased in contactwith said filter element.
 15. A fluid filter assembly as claimed inclaim 14 further comprising means to adjust the scraper to contact theinlet side of said filter element.
 16. A fluid filter assembly asclaimed in claim 15 wherein said means to adjust said scraper includes athreaded adjustment member coacting with said scraper and said scraperarm shoe.
 17. A fluid filter assembly of claim 2 wherein said nozzlemeans directs the pressurized cleaning fluid at an acute incident anglewith respect to the tangent to the inlet side of the filter element at apoint of contact of the directed pressurized cleaning fluid.
 18. Thefluid filter assembly of claim 17 wherein said nozzle means ispositioned at approximately a 45° angle with respect to the tangent atthe point of contact of the directed pressurized cleaning fluid withsaid inlet side of said filter element.
 19. A fluid filter assembly ofclaim 2 wherein said nozzle means comprises a nozzle conduit and atleast one nozzle mounted to said nozzle conduit.
 20. A fluid filterassembly of claim 1 further comprising a motor mounted to said body andsaid filter element mounted to said motor wherein when said motor isactivated, said motor rotates said filter element about a central axis.21. A method of modifying a filter assembly having a body with a chamberfor receiving a filter element and an inlet cavity;a filter elementattached to said body and positioned within said chamber through which afluid being filtered must pass, said filter element having an inlet sideand an outlet side through which the fluid being filtered passes fromsaid inlet cavity, through said inlet side and then through said outletside; and means for cleaning comprising: a hollow duct for collectingdislodged particulate matter, said duct mounted to said body andpositioned within said inlet cavity adjacent to said inlet side of saidfilter element, said duct and said filter element being movably mountedrelative to each other, wherein said duct includes a slot opening sothat said duct is in fluid communication with said inlet cavity; anelongated adjustable scraper extending in the longitudinal directionattached to said duct and slidably contacting said filter element inletside, said scraper substantially equal in length as said slot opening; afluid deflector attached to said duct, said deflector substantiallyequal in length as said scraper, wherein said deflector is positionedforwardly of said scraper and said slot opening of said duct ispositioned between said deflector and said scraper, said deflectorhaving a forwardly leading end positioned in close proximity to saidfilter element; an upper plate attached to said duct adjacent to anupper portion of said scraper and an upper portion of said deflector anda lower plate attached to said duct adjacent to a lower portion of saiddeflector and a lower portion of said scraper; a cleaning chamberdefined by said scraper, said deflector, said upper plate, said lowerplate and a portion of said duct containing said slot opening, saidcleaning chamber in fluid communication with said inlet chamber, wherebywhen a fluid to be filtered passes from the inlet chamber through thefilter element and through the outlet chamber and said duct and filterelement move relative to each other, a portion of the fluid is directedfrom said inlet chamber into said cleaning chamber and said duct, saidmethod comprising the steps of: A) attaching to said body a nozzle meansfor directing cleaning fluid maintained at a pressure greater than thepressure of the fluid being filtered against the inlet side of thefilter element for dislodging particulate matter from said inlet side ofthe filter element, said nozzle positioned within the inlet cavity andadjacent to said inlet side of the filter element and said means forcleaning; and B) coupling a pressurized cleaning fluid source to saidnozzle means.
 22. A fluid filter assembly comprising:a filter bodydefining a chamber, an inlet, an outlet, and a backwash outlet; acylindrical filter element positioned within said chamber and supportedby said body through which a fluid entering the inlet must pass to exitthe outlet, said filter element having an inlet side and an outlet side,said filter body and the inlet side of said cylindrical filter elementdefining an inlet cavity; means for cleaning the inlet side of thefilter element comprising: a hollow duct for collecting particulatematter dislodged from said filter element, said duct supported by saidbody and positioned within said inlet cavity adjacent to said inlet sideof said filter element, said duct and said filter element being movablerelative to each other, said duct including a slot opening so that saidduct is in fluid communication with said inlet cavity; a brush having aplurality of bristles attached to said duct and slidably contacting theinlet side of said filter element, said brush substantially equal inlength to said slot opening; a fluid deflector attached to said duct,said deflector substantially equal in length as said brush, saiddeflector being positioned forwardly of said brush, said slot opening insaid duct being positioned between said deflector and said brush, saiddeflector having a leading edge positioned in close proximity to saidfilter element; a cleaning chamber defined by said brush, saiddeflector, and said duct, said cleaning chamber in fluid communicationwith said inlet cavity; whereby when a fluid to be filtered passes fromthe inlet through the filter element and to the outlet and said duct andsaid filter element move relative to each other, fluid is directed fromsaid inlet cavity into said cleaning chamber and said duct through whichit can be exhausted to said backwash outlet.